Question
Given the following fragment that purports to convert from degrees Celsius to degrees Fahrenheit, answer the following questions:
double c = 20;
double f;
f = (9/5) * c + 32.0;
a. What value is assigned to f?
b. Explain what is actually happening, and what the programmer likely
wanted.
c. Rewrite the code as the programmer intended.
Answer
The statement executed using a program. The program is follows:
#include <iostream>
int main()
{
//declare and initialise variable
double c = 20;
//declare variable
double f;
//calculate the value of f
f = (9/5) * c + 32.0;
std::cout << "Value of f : "<<f;
return 0;
}
Sample Output:
Value of f : 52
a) The value assigned to f is 52.
b) The term (9/5) is evaluated as integer division because 9 and 5 are integers. The result will be 1 as rounding will take place and digits after decimal will be ignored. This is the reson for incorrect result.
c) The term (9/5) should be replaced with (9.0/5.0). Then it will be evaluated as double division.
Following is the updated program:
#include <iostream>
int main()
{
//declare and initialise variable
double c = 20;
//declare variable
double f;
//calculate the value of f
f = (9.0/5.0) * c + 32.0;
std::cout << "Value of f : "<<f;
return 0;
}
Sample Output:
Value of f : 68